Newer light sources, e.g., high-efficiency light sources, such as light-emitting diode (LED) light sources and compact fluorescent lamps (CFLs), require load regulation devices, such as ballasts or drivers, in order to illuminate properly. The load regulation device usually receives an alternating-current (AC) voltage from an AC power source, and regulates at least one of a load voltage generated across the light source or a load current conducted through the light source. The load regulation device may be configured to control the light output of the light source (e.g., to control the intensity or color of the light source). Example dimming methods may include a pulse-width modulation (PWM) technique, a constant current reduction (CCR) technique, and/or a combination of the PWM technique and the CCR technique. Examples of load regulation devices (e.g., such as LED drivers) are described in greater detail in commonly-assigned U.S. Pat. No. 8,492,988, issued Jul. 23, 2010, entitled CONFIGURABLE LOAD CONTROL DEVICE FOR LIGHT-EMITTING DIODE LIGHT SOURCE, and U.S. Pat. No. 8,680,787, published Mar. 25, 2014, entitled LOAD CONTROL DEVICE FOR A LIGHT-EMITTING DIODE LIGHT SOURCE, the entire disclosures of which are hereby incorporated by reference.
The load regulation device may be configured to control a connected light source (e.g., to adjust the intensity or color of the light source) in response to a control signal. The control signal may be an analog control signal or a digital control signal. The digital control signal may be, for example, a digital PWM control signal, a digital message transmitted using a communication protocol (e.g., a standard protocol, such as the digital addressable lighting interface (DALI) protocol, or a proprietary protocol, such as the ECOSYSTEM protocol), and/or the like. The analog control signal may be, for example, a “zero-to-ten-volt” (0-10V) control signal, a “ten-to-zero-volt” (10-0V) control signal, an analog pulse-width modulated (PWM) control signal, and/or the like. The analog control signal may be transmitted from a remote control device (e.g., an external 0-10V control device). The remote control device may be mounted in an electrical wallbox and may comprise an intensity/color adjustment actuator, e.g., a slider control. The remote control device may regulate a magnitude of the control signal (e.g., regulate a direct-current (DC) voltage level of the control signal) between a low-end magnitude (e.g., zero to one volt) to a high-end magnitude (e.g., nine to ten volts) in response to an actuation of the intensity/color adjustment actuator. The low-end magnitude may correspond to a minimum light level or color temperature of the light source, and the high-end magnitude may correspond to a maximum light level or color temperature of the light source. As the magnitude of the control signal is adjusted between the low-end magnitude and the high-end magnitude, one or more aspects of the light source may be adjusted accordingly. For example, the intensity level of the light output may be adjusted between the minimum light level and the maximum light level according to a dimming curve, the color (e.g., color temperature) of the light output may be controlled according to a color tuning curve, and/or the like.
When the control signal is an analog signal, the magnitude and/or strength of the control signal may be affected by interferences and/or electromagnetic properties of the components located between the remote control device and the load regulation device. For example, long wires that run from the remote control device to the load regulation device may degrade the magnitude of the control signal as received by the load regulation device (e.g., a voltage drop in the magnitude of a 0-10V control signal due to the resistance in the wires). This drop in the magnitude of the control signal may skew the normal dimming range of the light source. For example, instead of receiving a voltage having a magnitude of 1V as a signal to set the light level of the light source to a minimum level, the light source may receive a voltage having a magnitude of 0.8V. Similarly, instead of receiving a voltage having a magnitude of 9V as a signal to set the light level of the light source to a maximum level, the light source may receive a voltage having a magnitude of 8.8V.
The discrepancy between the magnitude of the originally-produced control signal and the actually-received control signal may be particularly noticeable when multiple lighting fixtures are controlled by the same control device but are installed at different distances from the remote control device. For example, the control signal received by one lighting fixture may deviate more or less from the original signal magnitude than that received by another lighting fixture. As such, the same control signal generated by the remote control device may produce different light intensities and/or colors at different lighting fixtures, causing undesirable visual effects in a multi-light environment (e.g., the light output inconsistency may be more perceptible towards the low end of the dimming range).